Key to species of Glypthelmins

1a. Ratio of body width/length larger than 7. Suctorial disc in ventral sucker present................. G. intestinalis

1b. Ratio of body width/length smaller than 6. Suctorial disc in ventral sucker absent....................................2.

2a. Perypharyngeal glands present ....................................................................................................... G. quieta

2b. Perypharyngeal glands absent......................................................................................................................3.

3a. Ratio of oral sucker/ventral sucker length smaller than 1:0.6.....................................................................4.

3b. Ratio of oral sucker/ventral sucker length larger than 1:0.7........................................................................9.

4a. Pharynx width larger than ventral sucker width..........................................................................................5.

4a. Pharynx width equal or smaller than ventral sucker width..........................................................................8.

5a. Symmetrical testes .............................................................................................................. G. californiensis

5b. Oblique testes...............................................................................................................................................6.

6a. Vitelline follicles confluent dorsally in the region between caecal bifurcation and ventral sucker ............... ................................................................................................................................................ G. tuxtlasensis

6b. Vitelline follicles confluent dorsally only at the level of testes...................................................................7.

7a. Uterine loops occupying the postcaecal space posteriorly to the end of body ................................ G. facioi

7b. Uterine loops occupying the intercaecal space posteriorly to the end of caeca............................... G. parva

8a. Asymmetrical distribution of the 2 fields of vitelline follicles along the body ................... G. brownorumae

8b. Symmetrical distribution of the 2 fields of vitelline follicles along the body ............................... G. shastai

9a. Uterine loops between ventral sucker and testes region; extracaecal uterine loops along the body present.. ....................................................................................................................................... G. pennsylvaniensis

9b. Uterine loops between ventral sucker and testes region absent; extracaecal uterine loops along the body absent........................................................................................................................................... G. hyloreus